JPH03704A - Photopolymerizable resin composition and recording medium - Google Patents

Abstract

PURPOSE:To obtain a photopolymerizable compsn. with high sensitivity suitable for a UV ink, a UV adhesive and a photosensitive litho printing plate, etc., utilizing photopolymn. by incorporating a radical-addition polymerizable ethylenically unsatd. compd. and an onium salt-contg. photopolymn. initiator. CONSTITUTION:In a photopolymerizable compsn. wherein a radical-addition polymerizable ethylenically unsatd. compd. (e.g. trimethylol triacrylate) and a photopolymn. initiator are incorporated as essential ingredients, an onium salt of formula I (wherein Ar<1>, Ar<2> and Ar<3> are each an aryl; R<1> is an alkyl, an aralkyl, an alkaryl, an alicyclic group, a heterocyclic, etc.) (e.g. compd. of formulas II and III) is incorporated as the photopolymn. initiator. A photopolymerizable compsn. with high sensitivity is obtd. by incorporating the onium salt and it is suitable for a UV ink, a UV adhesive, a photosensitive litho printing plate, etc., utilizing photopolymn.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a photopolymerizable composition suitable for UV inks, UV adhesives, photosensitive lithographic printing plates, etc. that utilize photopolymerization reactions, and for use in printers, copiers, etc. The present invention relates to a recording medium used in recording apparatuses such as machines and facsimiles, and particularly to a recording medium used in a recording method suitable for one-shot color recording.

[Prior art] Conventionally, fp4. ! Aromatic iodonium salts with counter anions such as sFa, 'FF, etc. are used as initiators for photocationic polymerization because they release strong Brønsted acids when irradiated with light (Annua IRe
view Mater, Set, , 173-19
0. (I3), 1983, etc.).

Furthermore, in recent years, the application of aromatic iodonium salts having these counter anions to radical polymerization systems has been studied.

For example, Fiber and Polymer Materials Research Institute Research Report No. 155 (I
(987), p. 87, describes a combination of diphenyliodonium hexafluorophosphate and p-dimethylaminobenzylidene derivatives as a highly sensitive photopolymerization initiator.

Furthermore, in JP-A-61-24495, the sensitivity of photosensitive microcapsules is improved by adding diphenyliodonium hexafluorophosphate to the inner phase of the photosensitive microcapsules.

However, these aromatic iodonium salts were developed as photoinitiators for cationic polymerization as described above, and have the undesirable property of releasing strong Brønsted acids upon decomposition.

Furthermore, these aromatic iodonium salts are soluble in water and may have disadvantages in producing photopolymerizable compositions and recording media.
In No. 495, when diphenyliodonium hexafluorophosphate is added to the oil phase (microcapsule internal phase) during microcapsule production, propylene carbonate is used in combination. This is because diphenyliodonium hexafluorophosphate is soluble in water, and if it is encapsulated as it is, it will elute in water, so an aprotic solvent such as propylene carbonate is used in combination to suppress elution from the oil phase to the water phase. it is conceivable that.

As described above, when the photopolymerization initiator is water-soluble, it may be necessary to use additional additives depending on the purpose of use.

Further, JP-A-62-143044 discloses a dye borate complex as a photopolymerization initiator.

[Problem to be solved by the invention]

An object of the present invention is to provide a radically polymerizable photopolymerizable composition and a high-sensitivity composition useful for improving the sensitivity of a recording medium, containing an onium salt that does not generate a strong Brønsted acid and is hardly soluble in water. An object of the present invention is to provide a photopolymerizable composition and a recording medium using the composition.

[Means for Solving the Problems 1] The present invention provides a photopolymerizable composition comprising as essential components a compound having an ethylenically unsaturated double bond capable of radical addition polymerization and a photopolymerization initiator. The following general formula (I) Ar'-I-Ar" = (I)B
(Ar'), R' [wherein Ar' s Ar'' and Ar' each independently represent an aryl group, R1 is an alkyl group, an aralkyl group, an alkaryl group, an alkenyl group, an aralkyl group, an alicyclic group, A photopolymerizable composition characterized by containing an onium salt represented by ], which represents a heterocyclic group, and a recording medium to which the composition is applied.

First, the photopolymerization initiator of general formula (I) will be explained.

Diphenyliodonium salts having the above-mentioned counter anions have been actively applied to radical polymerization systems in recent years, but the present inventors found that when diphenyliodonium salts are applied to radical polymerization systems, depending on the type of counter anion It was found that the sensitivity hardly changed. This shows that it is Raji. On the other hand, JP-A-6
2-143044, as a photopolymerization initiator,
In the dye borate complex, for example, the counter anion moiety (BPbsn-Cl3
) has been disclosed to contribute to radical generation.

Here, the present inventor has used the general formula CI as a photopolymerization initiator.
By using the compound represented by ), the present invention was completed by discovering an onium salt that does not produce a strong Brønsted acid upon decomposition, is almost insoluble in water, and has extremely high sensitivity.

The compound of general formula (I) has a cation moiety [Ar'-I
-Ar'' and the anion moiety [B(Ar3)sR'] both contribute to radical generation, which is thought to result in higher sensitivity than conventional onium salts.

In the formula, examples of the aryl group corresponding to Ar' % Ar'' and Ar3 include phenyl group, naphthyl group, substituted phenyl group, substituted naphthyl group, etc. Furthermore, examples of the substituent include alkyl group, alkoxy group, nitro group, and halogen atom. Examples include.

Examples of R1 include alkyl groups, aralkyl groups, alkaryl groups, alkenyl groups, aralkyl groups, alicyclic groups, and heterocyclic groups, and particularly preferred are alkyl groups.

Specific examples of the compound of general formula CI) include the following, but the present invention is not limited thereto.

0B, ◎) sn-CJ* The compound of general formula (I) does not have an effective absorption band above 300 nm, so it is not used alone, but in combination with a commonly used photopolymerization initiator. It has the effect of improving the sensitivity of the photopolymerization initiator.

Photopolymerization initiators that can be used in combination include benzyl derivatives, α-diketones such as camphorquinone, benzophenone derivatives, benzoin derivatives, xanthone derivatives, thioxanthone derivatives, ketocoumarin derivatives, chalcone derivatives,
Examples include ketones such as styryl styryl ketone derivatives.

Furthermore, the compound of general formula (I) can interact with various dyes or sensitizers to become a highly sensitive photopolymerization initiator.

Such dyes or sensitizers include coumarin dyes,
merocyanine dye, xanthine dye, acridine dye,
Examples include thiazine dyes, oxazine dyes, indoline dyes, triarylmethane dyes, and tetrabenzoporphyrins.

It is unclear why the sensitivity increases when the compound of general formula CI) is used in combination with a photopolymerization initiator, dye, or sensitizer, but This is thought to be because the onium salt decomposes due to electron transfer or energy transfer and radicals are generated.

Further, the compound of general formula (I) is a photopolymerization initiator used in combination,
About 1=10 to about 10:1 for dyes, sensitizers, etc.
(weight ratio), and it is also possible to use amines in combination as a promoter of the polymerization reaction.

Furthermore, the addition-polymerizable compound having an ethylenically unsaturated double bond, which is an essential component of the photopolymerizable composition of the present invention, refers to a compound having at least one ethylenically unsaturated double bond in its chemical structure. It has chemical forms such as monomers, oligomers, and polymers.

Examples include monomers such as methyl acrylate, methyl methacrylate, acrylonitrile, and acrylamide; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid; and ethylene glycol and triethylene glycol. , esters with aliphatic polyhydric polyol compounds such as tetraethylene glycol, trimethylolpropane, 1,3-butanediol, pentaerythritol, dipentaerythritol, and polyisocyanates (reacted with polyols as necessary). urethane acrylates, urethane methacrylates, and epoxy resins synthesized by the polyaddition reaction of alcohols and amines containing unsaturated double bonds, and urethane acrylates and urethane methacrylates, which are synthesized by the addition reaction of epoxy resins and acrylic acid or methacrylic acid. Examples include epoxy acrylates, polyester acrylates, spin acrylates, polyether acrylates, etc., but the present invention is not limited thereto.

In addition, as a polymer, the main chain has a skeleton such as polyalkyl, polyether, polyester, polyurethane, etc.
Examples include those in which a polymerizable reactive group such as an acrylic group, a methacrylic group, a cinnamoyl group, a cinnamylidene acetyl group, and a furyl acryloyl group are introduced into the side chain, but the present invention is not limited thereto. .

In addition, the photopolymerizable composition containing the above-mentioned photopolymerization initiator and a compound having an ethylenically unsaturated double bond as essential components may further contain known binders, colorants, etc. according to the purpose of use. It can be included.

As the binder, any organic polymer may be used. Examples of such organic polymers include polyacrylic acid alkyl esters such as polymethyl acrylate and polyethyl acrylate; Polymethacrylic acid alkyl esters such as polymethyl methacrylate and polyethyl methacrylate, methacrylic acid copolymers, acrylic acid copolymers, maleic acid copolymers, or chlorinated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, poly Examples include vinyl chloride, polyvinylidene chloride, polyacrylonitrile, or copolymers thereof, as well as polyvinyl alkyl ether, polyethylene, polypropylene, polystyrene polyamide, polyurethane, chlorinated rubber, cellulose derivatives, polyvinyl alcohol, polyvinylpyrrolidone, etc., but the present invention is not limited to these.

These polymers may be used alone or in a mixture of two or more in an appropriate ratio, and may be used as binders, such as compatible or
Waxes may be used without being limited to incompatible polymers, and any amount of these polymers can be mixed into the entire composition.

The colorant is a component contained in order to form an optically recognizable image, and various pigments and dyes are used as appropriate. Examples of such pigments and dyes include inorganic pigments such as carbon black, yellow lead, molybdenum red, and red iron.
Banza Yellow, Benzidine Yellow, Brilliant Carmine 6B.

Examples include organic pigments such as Lake Red C1 Permanent Red F5R and Phthalocyanine Blue, leuco dyes, phthalocyanine dyes, and colorants such as Victoria Blue Lake and Fast Sky Blue.

The photopolymerizable composition of the present invention is used by appropriately mixing the various components described above depending on the purpose of use.

For example, for use in photosensitive lithographic printing plates, the mixture may be dissolved in a suitable solvent to
A photosensitive layer is formed by coating on a support such as polypropylene, polystyrene, etc.) or a metal plate (aluminum, zinc, etc.), imagewise exposed using a light source such as a high-pressure mercury lamp, fluorescent lamp, or XS clamp, and processed with a developer. The unexposed areas of the photosensitive layer may be removed, and finally a gum solution may be applied. The photopolymerizable composition of the present invention has high sensitivity and is effective in shortening the time for plate production.

Further, as the coloring agent, a substantially colorless color former may be used to develop the color by reacting with a color developer in a subsequent step. Such color formers include substantially colorless compounds having a lactone, lactam, sultone, spiropyran, ester or amide structure in their partial skeleton, such as triarylmethane compounds, bisphenylmethane compounds, xanthine compounds, and fluorans. , thiazine compounds, spiropyran compounds, etc.

Cyan, magenta and yellow precursors useful in the present invention may be selected from commercially available materials. React・
Yeo - (Reakt Yellow) (I8B)
(BASF product), Copikem
I and Cobichem XIV (products of Hilton Davis Chemical Company) are useful yellow color formers. Cyan B-29663 (Hilton
Davis (experimental compound), Cobichem
Davis product) and U.S. Patent Box 4.322.352
The color former described in the specification is a useful cyan color former,
and Cobichem XX (a Hilton Davis product) and Pergascript Red (Pergascript
t Red (a Ciba-Geigy product) is useful as a magenta color former.

Furthermore, as a color developer, for example, clay minerals such as acid clay, activated clay, and attapulgite, organic acids such as tannic acid, gallic acid, and propyl gallate, phenol-formaldehyde resins, phenolacetylene condensation resins, and at least one Acidic polymers such as condensates of formaldehyde and organic carboxylic acids having hydroxyl groups, zinc salicylate, tin salicylate, zinc 2-hydroxynaphthoate, zinc 3.5-di-t-butylsalicylate, 3-cyclohexyl -5-(α,α-dimethylbenzyl)zinc salicylate (U.S. Patent Box 3.864.146
and oil-soluble metal salts of phenol-formaldehyde novolak resins (see, e.g., U.S. Patent No. 3,672,935). , No. 3.7
32.120, 3.737.410), zinc-modified oil-soluble phenol-formaldehyde resins, such as those disclosed in U.S. Patent No. 3.732.120, zinc carbonate, and the like; It is a mixture of them.

Furthermore, the photopolymerizable composition of the present invention can be used as a recording medium for an image forming system that utilizes a photopolymerization reaction.

In particular, U.S. Patent No. 4.399.209, JP
It is suitable as a recording medium for the image forming method disclosed in Specification No. 1-24495 and Japanese Patent Application Laid-open No. 174195/1984. Here, the method described in Japanese Unexamined Patent Publication No. 174195/1988 will be briefly explained.

JP-A-62-174195 discloses a method for recording at least one type of energy among the plurality of types of energy on a transfer recording medium having a transfer recording layer in which the physical properties governing transfer characteristics change when a plurality of types of energy are applied. This is an image forming method in which a transferred image is formed by applying the plurality of types of energy under conditions that correspond to information, and then transferred onto a recording medium.

In the image forming method, a photopolymerization initiator and a compound having an ethylenic saturated double bond (hereinafter referred to as a polymerizable monomer) capable of addition polymerization are used, using light energy and thermal energy, and the thermal energy is made to correspond to recorded information. Also, a method of applying the colorant to a transfer recording layer which is in a solid phase at room temperature and which includes a colorant as an essential component will be explained.

The transfer recording layer has a softening temperature T$, and its viscosity decreases rapidly at temperatures above Ts. Here, the transfer recording layer is uniformly irradiated with light corresponding to the absorption wavelength of the photopolymerization initiator contained in the transfer recording layer, and at the same time, a heating means such as a thermal head is used to raise the transfer recording layer to a temperature of Ts or higher according to the recorded information. When partially heated, the viscosity of the portion heated above Ts rapidly decreases, the diffusion rate of the photopolymerization initiator and polymerizable monomer in the transfer recording layer increases, and the polymerization reaction rapidly proceeds. On the other hand, in the non-heated area, the viscosity of the transfer recording layer does not decrease, so the photopolymerization initiator and polymerizable monomer do not diffuse sufficiently and the polymerization reaction occurs only partially. If the recording medium on which the transferred image has been formed is brought into pressure contact with the recording medium to be transferred and heated to a predetermined temperature necessary for transfer, for example, a temperature higher than Ts, the polymerization reaction will partially occur in the non-heated part of the thermal head. The portion where only a portion of the image is generated is transferred to the transfer recording medium, and the heated portion of the thermal head has sufficient polymerization, so the adhesiveness with the transfer target recording medium is low, and the transfer is not performed. In this way, an image is formed using light energy and thermal energy.

In addition, although the softening temperature Ts of the transfer recording layer was explained above as a physical property value that governs the transfer characteristics and polymerization reaction amount of the transfer recording layer, in addition to this, the glass transition point, melting temperature, etc. of the transfer recording layer are also explained. Feel free to use it.

In the present invention, the transfer recording layer may be a continuous layer coated on a support, or may be coated with a particulate element, and furthermore, the transfer recording layer may be coated with light and thermal energy to change the transfer characteristics. It may also be composed of microcapsules whose core material is a variable composition.

In addition, in order to form a multicolor image in the present invention, a transfer recording layer is formed of particulate bodies or microcapsules containing colorants exhibiting several different color tones, and a photopolymerization initiator contained therein is formed. This can be done by changing the wavelength range to which the light is sensitive.

Next, a multicolor image forming method that can bring out the effects of the present invention most will be described. FIGS. 1-a and 1-c are partial views showing the relationship between the transfer recording medium and the thermal head of the present invention.

The recording medium 1 of the present invention has a transfer recording layer 1a on a support lb.
It is configured with the following. The transfer recording layer 1a is a layer in which minute image forming elements 3 are distributed, and each image forming element 3 is
For example, in the example shown in FIG. 1, each image forming element 3 contains cyan (C).
), magenta (M), and yellow (Y). Here, each of the Y, M, and C image forming elements contains a photopolymerization initiator having a different photosensitive wavelength range.

Next, a specific example of the image forming method using the recording medium of the present invention will be shown. First, the transfer recording medium 1 is stacked on the thermal head 2, and light is irradiated so as to cover the entire heat generating part of the thermal head 2. The irradiated light is sequentially irradiated with wavelengths that the image forming element 3 reacts with. For example, if the image forming element 3 is colored cyan, magenta, or yellow, the wavelengths λ(C), λ (M) and (Y) are sequentially irradiated with light.

That is, first, light of wavelength λ(Y) is irradiated from the transfer recording layer 1a side of the transfer recording medium 1, and the heating elements 2b, 2d, 2e, and 2f of the thermal head 2, for example, are caused to generate heat. Then, of the image forming element 3 containing the yellow colorant, the image forming element 3 to which both heat and light of wavelength λ(Y) are applied (the hatched part in FIG. 1-a) (Hereinafter, the cured image forming element is indicated by hatching.)
hardens.

Next, as shown in FIG.
When the light of (M) is irradiated and the heating elements 2a, 2e, and 2f generate heat, heat and light of wavelength λ(M) are added to the image forming element 3 containing the magenta colorant. The image forming element 3 is cured. Furthermore, as shown in Figure 1-0, when light of wavelength λ(C) is irradiated and a desired heating element is heated, the image forming element 3 to which the light and heat have been applied is cured, and the final image is formed. A transferred image is formed on the transfer recording layer 1 by the image forming element 3 that has not been cured.

The transfer image formed as described above is transferred to the transfer recording medium by being pressed against the transfer recording medium and heated to a predetermined temperature [i.e., the unhatched Y in Figure 1-- M and C image forming elements 3 are transferred].

Here, by simultaneously using the photopolymerization initiator contained in the recording medium of the above-mentioned image forming method and the compound represented by the general formula (I), high photosensitivity can be obtained, and the heating time of the recording medium can be shortened. Therefore, the recording speed is improved.

Further, in the image forming method described in the specification of US Pat. Contains as an essential component (color development by reaction with a color developer). Also in this image forming method, photosensitivity and recording speed can be improved by using the photopolymerization initiator and the compound of general formula (I) together.

〔Example〕

The present invention will be specifically explained below using Examples.

It was synthesized by the method shown in the reaction formula below.

H3O.

B Ph s nJ u The obtained onium salt is a pale yellow solid with a melting point of 119~
It showed 122°C. Further, FIG. 9 shows an IR diagram.

1. As a compound having an ethylenically unsaturated double bond, 20 g of trimethylol triacrylate, as a binder, PMMA manufactured by DuPont (Elvacite 2041)
15 g of the compound shown in Table 1 as a photopolymerization initiator, 0.0 g of ethyl-p-dimethylaminobenzoate.
5g, a compound represented by general formula (I) (Table 1),
The solution was dissolved in dichloromethane at about 100 mA using a spinner, and coated on an aluminum plate to a thickness of about 4 U using a spinner. Next, on this photosensitive layer, polyvinyl alcohol (PVA) was applied as an antioxidant layer to a thickness of about 3 μm to prepare a sample.

Place an optical wedge (optical density 0 to 10 steps) on top of this sample.
After exposure for 15 seconds with a 50μ are shown in Table 1.

Also, the sensitivity when the compound of general formula (I) is replaced with diphenyliodonium hexafluorophosphate, and the sensitivity when the compound of general formula (I) is replaced with one dye borate described in JP-A-62-143044. Indicates sensitivity.

As can be understood from the results in Table 1, when the compound of general formula (I) is used in combination with a photopolymerization initiator, when known diphenyliodonium hexafluorophosphate is used in combination, and in JP-A No. 62-143044, It can be seen that the sensitivity is higher than when using the dye borate complex described in the specification.

1O1+111 Image formation using light and thermal energy was performed in the image forming method described in JP-A-62-174195.

(Preparation of recording medium) 100 g of water and 26 g of isobutylene-maleic anhydride copolymer (20.6%, manufactured by Kureha Chemical Co., Ltd.) were mixed,
3.1g of pectin was added to this and stirred for 20 minutes.
The pH was then adjusted to 4.0 with a 20% sulfuric acid solution to 0.
2 g of Photoroll (manufactured by BASF) was added. While stirring this with a homomixer at 3000 rpm,
A solution prepared by dissolving 20 g of the ingredients shown in the table in 30 g of chloroform was added over 10 to 15 seconds, and emulsification was continued for 10 minutes.

The emulsion was transferred to a beer force of 500° and stirred with a stirring blade for 1 to 2 hours, and then the solvent was distilled off.

Next, 8.3 g of urea solution (50 wt%), 0.4 g of resorcinol dissolved in 5 g of water, 10.7 g of formalin (37%) and 0,6 dissolved in water of 1 (b*j)
g of ammonium sulfate were added at 2 minute intervals.

After the temperature was raised to 60° C. and stirring was continued for 3 hours, the temperature was lowered and the pH was adjusted to 2.0 with a 20% caustic soda solution. After filtering this capsule liquid, 1000t twice! This was washed with water and dried to obtain a microcapsule-shaped image forming element.

As shown in FIG. 2, this image forming element is a microcapsule in which a core 1c is covered with a shell 1d, and the particle size is 7 to 15.
μ, and the average particle size was lθμ.

Next, a polyester adhesive (LP-022, manufactured by Nippon Gosei Chemical Industry Co., Ltd.) was applied as an adhesive layer 1e to a thickness of about 1 μm onto the PET film lb as a support. An excess amount of the microcapsules was sprinkled onto the adhesive layer, and the excess image forming element not attached to the adhesive was brushed off.

Next, the transfer recording media were pressed against each other at 1 kgf/cm'', and the speed was set at 300 mm/min between rollers each made of a 40 mm diameter aluminum roller coated with 1 mm thick silicone rubber having a hardness of 70 degrees. At this time, the surface temperature of each roller was maintained at 80° C. After passing between the rollers, the image forming element on the adhesive layer was firmly fixed to the PET film.

Through the above steps, a transfer recording medium 1 as shown in the schematic cross-sectional view of FIG. 2 was obtained.

(Evaluation of Sensitivity) Next, the recording medium 1 produced by the above method was wound into a roll and assembled into the apparatus shown in FIG. 3.

The thermal head 2 was an A4 size line type with 8 dots/mm and heat generating element rows arranged at the edge portion, and was pressed against the heat generating elements by the tension of the recording medium 1. Then, chemical lamps 4 were placed at opposing locations. As the chemical lamp 4, a lamp (manufactured by Toshiba, F10A70E35/33T15) with a peak wavelength of 335 nm was used, matching the sensitive wavelength range of the photopolymerization initiator.

Next, the heat generation of the thermal head 2 is controlled according to the image signal. In this embodiment, since the transfer recording layer is treated with light and heat, the softening temperature rises and the transfer start temperature rises, so negative recording and Become. That is, the thermal head 2 is controlled such that it does not energize when a mark signal (magenta) is received, but energizes and generates heat when it is not a mark signal (white).

The energizing energy during this heat generation is 0.8W/dotX
1 sec, and the chemical lamp 4 synchronizes with the signal of the thermal head 2 to uniformly irradiate X m5ec light while controlling and driving the thermal head 2 according to the image signal in the manner described above to generate 2 X m5ec/line. The recording medium is conveyed by a stepping motor and a drive rubber roll in synchronization with a repetition period of .Next, as shown in FIG. It was conveyed while being sandwiched between rolls 8 and pinch rolls 9. The heat roll 8 has a 300W heater 7 inside, and the surface
The heater 7 was controlled to maintain the surface of the aluminum roll coated with mm-thick silicone rubber at an arbitrary temperature in the range of 50 to 150°C. The pinch roll 9 is a silicone rubber roll with a hardness of 50 degrees according to the JIS rubber hardness tester, and the pressure is 1 to 1.5 kg.
/c+n”.

Controlling the heat roll 8 in the range of 110°C to 130°C,
After the plain paper was conveyed over the transfer recording layer, the support 1b was peeled off, and the minimum time X m5ec for obtaining an image was determined and defined as the sensitivity. That is, the smaller the value of X, the higher the sensitivity. Moreover, the obtained image was a high-quality image with good fixability. The results are shown in Table 4.

Furthermore, the composition shown in Table 2 was dissolved in dichloromethane, and P
A recording medium was prepared by coating ET to a thickness of 3J1 m and then providing a PVA layer of 3 μm, and sensitivity evaluation was performed using the method described above (PVAl1if was removed by washing with water during the transfer process).

Table 3 also shows the results when diphenyliodonium hexafluorophosphate was used in place of the compound of general formula (I).

Table: Sensitivity A is in a microcapsule state. Sensitivity B remains P
Coated on ET.

As can be seen from Table 3, by adding the compound of general formula (I), the sensitivity is significantly improved in both microcapsule form and direct application.

In particular, when it is made into microcapsules, the sensitivity is significantly increased compared to when diphenyliodonium hexafluorophosphate is used. This is considered to be because diphenyliodonium hexafluorophosphate was eluted into water during the microcapsule manufacturing process.

As is clear from the above, the compound of general formula (I) is effective in improving the sensitivity of a recording medium, and even if an aqueous substance is used during the manufacturing process of the recording medium, the sensitivity will not be adversely affected.

A method for forming a multicolor image using the image forming method described in Japanese Patent Application Laid-Open No. 62-17.4195 will be described below.

First, the composition shown in Example 1O and the composition shown in Table 4 below were each made into microcapsule-shaped image forming elements in the same manner as in Example 1O. Next, equal amounts of microcapsules having magenta and yellow hues obtained as described above were coated with an adhesive in the same manner as in Example 10.
It was fixed on a T and used as a recording medium. (See Figure 5) Here, 4,4°-dimethoxybenzyl and 3,3°-carbonylbis(7-dinithylaminocoumarin) have the absorption characteristics shown in Figures 6 and 7, respectively (in chloroform). .

The transfer recording medium 1 produced by the above method was installed in the apparatus shown in FIG. However, the chemical lamp 4 is a lamp A (with a peak wavelength of 335 nm) in accordance with the light absorption characteristics of the photopolymerization initiator.
Toshiba, FIOA70E35/33T15”) and lamp B with a peak wavelength of 450 nm (Toshiba, F10A70B)
/33T15) were placed.

The transfer record ffJ1a has a property that when light and heat of a predetermined wavelength are applied, the softening point temperature increases and it is no longer transferred to the recording paper. When recording magenta color, electricity is not applied to the heating element corresponding to the magenta color of the image signal in the heating element row of the thermal head, and a current of 5 m5ec is applied to the portion corresponding to the white color of the image signal (the recording medium is white). Turn on electricity and simultaneously irradiate lamp A uniformly for 8 m5ec.

Next, when recording yellow, 7 seconds after the end of the lamp A irradiation.
After m5ec has elapsed, that is, 15m5 from the above-mentioned energization time.
After ec, a portion of the heating element of the thermal head corresponding to the yellow color of the image signal is energized for 7 m5ec, and at the same time, lamp B is uniformly irradiated for 10m5ec.

By controlling the thermal head according to the image signals of magenta, yellow, and white in the manner described above, a negative image is formed on the transfer recording layer, and the image is transferred onto plain paper in the same manner as in Example IO.
Color recording is done in one shot.

〔Effect of the invention〕

As explained above, as a photopolymerization initiator, general formula (I)
By containing the onium salt, it does not elute into water during microcapsule production, and since Bronsted acid is not released during decomposition, there is no adverse effect on radical polymerization, and the sensitivity of the recording medium is improved. This is something that can be improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of transfer recording using the recording medium of the present invention.
Figures 3 and 4 are schematic diagrams of an apparatus for performing transfer recording using the recording medium of the present invention, Figures 2 and 5 are configuration diagrams of the transfer recording medium, and Figures 6 and 7 are photopolymerization FIG. 8 is a UV chart showing the light absorption characteristics of the initiator, FIG. 8 is a timing chart, and FIG. 9 is an IR chart of the compound obtained in the production example. 1...Recording medium 1a...Transfer recording layer 1b...Support lc, I
g, lh...core 1d...shell le...
Adhesive layer 2... Thermal head 4... Lamp 6... Supply roll 8... Heat roll lO... Plain paper 12... Recorded image 3... Image forming element 5... Control Circuit 7... Heater 9... Pinch roll 11... Winding roll

Claims (1)

[Scope of Claims] 1. In a photopolymerizable composition containing as essential components a compound having an ethylenically unsaturated double bond capable of radical addition polymerization and a photopolymerization initiator, as the photopolymerization initiator, the following general formula ( I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・( I
) [In the formula, Ar^1, Ar^2 and Ar^3 each independently represent an aryl group, and R^1 represents an alkyl group, an aralkyl group, an alkaryl group, an alkenyl group, an aracynyl group, an alicyclic group, a hetero Represents a ring group. ] A photopolymerizable composition comprising an onium salt represented by the following. 2. A transfer recording layer is provided on the support, the physical properties governing the transfer characteristics of which change when light energy is applied in accordance with the image recording information, and the transfer recording layer contains at least a coloring material and light energy. A recording medium formed from an image-forming element that is solid at room temperature and comprising a sensitive component that becomes sensitive when the sensitive component is applied, and the sensitive component is the photopolymerizable composition according to claim 1. . 3. Having a transfer recording layer on a support whose physical properties governing the transfer characteristics change by simultaneously applying at least one type of energy of light and thermal energy corresponding to image recording information; The recording layer is formed from an image forming element that is solid at room temperature and includes at least a coloring material and a sensitive component that becomes sensitive upon application of light energy and thermal energy, and the sensitive component is the photosensitive component according to claim 1. A recording medium characterized by being a polymerizable composition.